Average local ionization potential within the framework of the electron localization function

In this work we explore new insights arising from simple indices intended to measure the average local vertical ionization energy associated to ELF valence population basins. The model has been computationally tested on simple isothiocyanate compounds (R-N=C=S) revealing that the proposed relationships correctly establish both the inductive and electronegativity effects of electronegative groups along the examined series, i.e., methyl- < germyl- < hydrogen- < acetyl- < chlorodifluoroacetyl-, in agreement with the available experimental observations. The proposed energetical descriptors are expected to contribute to the search of relationships between the spatial topology of electronic populations and energetical aspects of the bonding. The present results enhance the possibility of gaining insight into chemical bonding and reactivity within the ELF topological-defined framework of chemical rationalization.